This application claims the priority of German patent document 100 52 424.9, filed Oct. 23, 2000, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an arrangement for determining the position of a light source.
Many light source locating arrangements are known to the art. For example, German patent documents DE 42 14 136 discloses the use of a rectangular slit, through which the light from the light source shines onto a detector line. From the areas in which the light of the two legs of the slit shines onto the detector line the incidence angle of the light can be determined, and thus the position of the light source relative to the measurement arrangement. With such an arrangement biaxial measurements are possible. Similarly, Japanese patent document JP 6 106 6117 provides a two-dimensional detector array, with which light shining in through a single slit is recorded and from which also the incidence angle is determined. This arrangement enables only uniaxial measurements.
German patent document DE 198 38 460 on the other hand, shows the use of a shadow mask, which creates one or more light-shadow boundaries on a detector line or detector array, thus enabling uniaxial or biaxial measurements of the incidence angle of light.
U.S. Pat. No. 5,640,241 uses, among other things, a two-dimensional detector array, onto which light shines through a cross slit, permitting a biaxial measurement of the incident light.
In U.S. Pat. No. 5,499,098, the light from a light source shines onto detector lines or a detector array. The light source is partially shaded by an arrangement that is located in a plane in front of the respective detector and comprises a transparent film or a transparent plate, which in certain areas is equipped with a light blocking structure. The shadow of the structure is used to determine the incidence direction of the light.
The disadvantage of these known prior are devices is that the depiction of the arrangements that permit the incident light to penetrate to the detector elements and/or cast a shadow onto the detector devices are dependent upon the incidence angle of the impinging light. Especially in the case of relatively large incidence angle deviations between the normal line and the detector plane, this feature can lead to large distortions of the depiction, and thus to measurement inaccuracies.
One object of the present invention, therefore, is to provide an arrangement for determining the position of an available light source that provides consistent measurement accuracy, independently of the incidence angle of the incident light.
This and other objects and advantages are achieved by the light source position determination arrangement according to the invention, which includes a light-sensitive detector device, together with an arrangement for shadowing a portion of the light from the light source shining onto the detector device, arranged in a plane that is spaced from the detector device. According to the invention, the shadowing arrangement is formed by at least one rotationally symmetrical body, so that the depiction of the body is independent from the incidence angle of the incident light.
The shadowing arrangement can have an essentially random diameter as long as a clear depiction is possible on the detector device within the desired angle ranges. Preferably however a body with a small diameter is used in order to enable as fine a resolution as possible, and to cover as large an angle range of the incidence angle as possible. In an advantageous embodiment, a wire or a similar body can be used to provide the shadow. In this case, it may be sufficient to design the detector device as a one-dimensional detector line for the one-dimensional, uniaxial determination of the incidence angle.
If biaxial measurement of the incidence angle of the light is desired, the shadowing arrangement must contain a two-dimensional expansion; in particular, it may be formed by rotationally symmetrical bodies arranged in a cross-shaped manner in the plane. Here as well, with basically any random diameter of the body, it may be preferred that the shadowing arrangement be formed by bodies with the smallest possible diameter (wires, for example), arranged in a cross-shaped manner in the plane. For biaxial measurement, the detector device has a two-dimensional detector array.
The above arrangements can be applied in a solar sensor used to determine the incidence angle of sunlight, such as the one used in aerospace technology, for determining the position of a spacecraft relative to the sun.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.